<template>
  <view class="uni-indexed-list" ref="list" id="list">
    <!-- #ifdef APP-NVUE -->
    <list
      class="uni-indexed-list__scroll"
      scrollable="true"
      show-scrollbar="false"
    >
      <cell
        v-for="(list, idx) in lists"
        :key="idx"
        :ref="'uni-indexed-list-' + idx"
      >
        <!-- #endif -->
        <!-- #ifndef APP-NVUE -->
        <scroll-view
          :scroll-into-view="scrollViewId"
          class="uni-indexed-list__scroll"
          scroll-y
        >
          <view
            v-for="(list, idx) in lists"
            :key="idx"
            :id="'uni-indexed-list-' + idx"
          >
            <!-- #endif -->
            <uni-indexed-list-item
              :list="list"
              :loaded="loaded"
              :idx="idx"
              :showSelect="showSelect"
              @itemClick="onClick"
            ></uni-indexed-list-item>
            <!-- #ifndef APP-NVUE -->
          </view>
        </scroll-view>
        <!-- #endif -->
        <!-- #ifdef APP-NVUE -->
      </cell>
    </list>
    <!-- #endif -->
    <view
      :class="touchmove ? 'uni-indexed-list__menu--active' : ''"
      @touchstart="touchStart"
      @touchmove.stop.prevent="touchMove"
      @touchend="touchEnd"
      class="uni-indexed-list__menu"
    >
      <view
        v-for="(list, key) in lists"
        :key="key"
        class="uni-indexed-list__menu-item"
      >
        <text
          class="uni-indexed-list__menu-text"
          :class="
            touchmoveIndex == key ? 'uni-indexed-list__menu-text--active' : ''
          "
          >{{ list.key }}</text
        >
      </view>
    </view>
    <view v-if="touchmove" class="uni-indexed-list__alert-wrapper">
      <text class="uni-indexed-list__alert">{{
        lists[touchmoveIndex].key
      }}</text>
    </view>
  </view>
</template>
<script>
import uniIcons from '../uni-icons/uni-icons.vue'
import uniIndexedListItem from './uni-indexed-list-item.vue'
// #ifdef APP-NVUE
const dom = weex.requireModule('dom')
// #endif
// #ifdef APP-PLUS
function throttle (func, delay) {
  var prev = Date.now()
  return function () {
    var context = this
    var args = arguments
    var now = Date.now()
    if (now - prev >= delay) {
      func.apply(context, args)
      prev = Date.now()
    }
  }
}

function touchMove (e) {
  const pageY = e.touches[0].pageY
  const index = Math.floor((pageY - this.winOffsetY) / this.itemHeight)
  if (this.touchmoveIndex === index) {
    return false
  }
  const item = this.lists[index]
  if (item) {
    // #ifndef APP-NVUE
    this.scrollViewId = 'uni-indexed-list-' + index
    this.touchmoveIndex = index
    // #endif
    // #ifdef APP-NVUE
    dom.scrollToElement(this.$refs['uni-indexed-list-' + index][0], {
      animated: false
    })
    this.touchmoveIndex = index
    // #endif
  }
}
const throttleTouchMove = throttle(touchMove, 40)
// #endif

/**
 * IndexedList 索引列表
 * @description 用于展示索引列表
 * @tutorial https://ext.dcloud.net.cn/plugin?id=375
 * @property {Boolean} showSelect = [true|false] 展示模式
 * 	@value true 展示模式
 * 	@value false 选择模式
 * @property {Object} options 索引列表需要的数据对象
 * @event {Function} click 点击列表事件 ，返回当前选择项的事件对象
 * @example <uni-indexed-list options="" showSelect="false" @click=""></uni-indexed-list>
 */
export default {
  name: 'UniIndexedList',
  components: {
    uniIcons,
    uniIndexedListItem
  },
  props: {
    options: {
      type: Array,
      default () {
        return []
      }
    },
    showSelect: {
      type: Boolean,
      default: false
    }
  },
  data () {
    return {
      lists: [],
      winHeight: 0,
      itemHeight: 0,
      winOffsetY: 0,
      touchmove: false,
      touchmoveIndex: -1,
      scrollViewId: '',
      touchmoveTimeout: '',
      loaded: false
    }
  },
  watch: {
    options: {
      handler: function () {
        this.setList()
      },
      deep: true
    }
  },
  mounted () {
    setTimeout(() => {
      this.setList()
    }, 50)
    setTimeout(() => {
      this.loaded = true
    }, 300)
  },
  methods: {
    setList () {
      const index = 0
      this.lists = []
      this.options.forEach((value, index) => {
        if (value.data.length === 0) {
          return
        }
        const indexBefore = index
        const items = value.data.map(item => {
          const obj = {}
          obj.key = value.letter
          obj.name = item
          obj.itemIndex = index
          index++
          obj.checked = item.checked ? item.checked : false
          return obj
        })
        this.lists.push({
          title: value.letter,
          key: value.letter,
          items: items,
          itemIndex: indexBefore
        })
      })
      // #ifndef APP-NVUE
      uni
        .createSelectorQuery()
        .in(this)
        .select('#list')
        .boundingClientRect()
        .exec(ret => {
          this.winOffsetY = ret[0].top
          this.winHeight = ret[0].height
          this.itemHeight = this.winHeight / this.lists.length
        })
      // #endif
      // #ifdef APP-NVUE
      dom.getComponentRect(this.$refs.list, res => {
        this.winOffsetY = res.size.top
        this.winHeight = res.size.height
        this.itemHeight = this.winHeight / this.lists.length
      })
      // #endif
    },
    touchStart (e) {
      this.touchmove = true
      const pageY = e.touches[0].pageY
      const index = Math.floor((pageY - this.winOffsetY) / this.itemHeight)
      const item = this.lists[index]
      if (item) {
        this.scrollViewId = 'uni-indexed-list-' + index
        this.touchmoveIndex = index
        // #ifdef APP-NVUE
        dom.scrollToElement(this.$refs['uni-indexed-list-' + index][0], {
          animated: false
        })
        // #endif
      }
    },
    touchMove (e) {
      // #ifndef APP-PLUS
      const pageY = e.touches[0].pageY
      const index = Math.floor((pageY - this.winOffsetY) / this.itemHeight)
      if (this.touchmoveIndex === index) {
        return false
      }
      const item = this.lists[index]
      if (item) {
        this.scrollViewId = 'uni-indexed-list-' + index
        this.touchmoveIndex = index
      }
      // #endif
      // #ifdef APP-PLUS
      throttleTouchMove.call(this, e)
      // #endif
    },
    touchEnd () {
      this.touchmove = false
      this.touchmoveIndex = -1
    },
    onClick (e) {
      const { idx, index } = e
      const obj = {}
      for (const key in this.lists[idx].items[index]) {
        obj[key] = this.lists[idx].items[index][key]
      }
      const select = []
      if (this.showSelect) {
        this.lists[idx].items[index].checked = !this.lists[idx].items[index]
          .checked
        this.lists.forEach((value, idx) => {
          value.items.forEach((item, index) => {
            if (item.checked) {
              const obj = {}
              for (const key in this.lists[idx].items[index]) {
                obj[key] = this.lists[idx].items[index][key]
              }
              select.push(obj)
            }
          })
        })
      }
      this.$emit('click', {
        item: obj,
        select: select
      })
    }
  }
}
</script>
<style scoped>
.uni-indexed-list {
  position: absolute;
  left: 0;
  top: 0;
  right: 0;
  bottom: 0;
  /* #ifndef APP-NVUE */
  display: flex;
  /* #endif */
  flex-direction: row;
}

.uni-indexed-list__scroll {
  flex: 1;
}

.uni-indexed-list__menu {
  width: 24px;
  background-color: lightgrey;
  /* #ifndef APP-NVUE */
  display: flex;
  /* #endif */
  flex-direction: column;
}

.uni-indexed-list__menu-item {
  /* #ifndef APP-NVUE */
  display: flex;
  /* #endif */
  flex: 1;
  align-items: center;
  justify-content: center;
}

.uni-indexed-list__menu-text {
  line-height: 20px;
  font-size: 12px;
  text-align: center;
  color: #aaa;
}

.uni-indexed-list__menu--active {
  background-color: rgb(200, 200, 200);
}

.uni-indexed-list__menu-text--active {
  color: #007aff;
}

.uni-indexed-list__alert-wrapper {
  position: absolute;
  left: 0;
  top: 0;
  right: 0;
  bottom: 0;
  /* #ifndef APP-NVUE */
  display: flex;
  /* #endif */
  flex-direction: row;
  align-items: center;
  justify-content: center;
}

.uni-indexed-list__alert {
  width: 80px;
  height: 80px;
  border-radius: 80px;
  text-align: center;
  line-height: 80px;
  font-size: 35px;
  color: #fff;
  background-color: rgba(0, 0, 0, 0.5);
}
</style>
